Development of a new wastebin sounds like an easy task. It’s not! At least when it should be used for dangerous waste. Add functional design and it gets even worse.
Mezonic have developed a full plastic, patent pending, combined storage and transportation container for solid and liquid waste. Norner was engaged by Mezonic during their development of the, so far, world’s largest UN-certified injection moulded container for dangerous goods. Our expertise was needed in material selection, mould improvements and optimization of processing conditions. In this article we share some of the many lessons learned during this challenging and, in the end, very successful project.
All parts of the CC container are produced from injection moulded high-density polyethylene. This eliminates corrosion problems and adds durability. It is designed for high strength with shock absorbing ribs on the lid and at the bottom of the container. The design also makes the bin stackable which enable efficient in transportation.
Mezonic aimed to make the World’s largest UN-certified injection moulded container for dangerous goods. To overcome this challenge, the best material had to be selected, processing of the thick-walled big container optimised and certification test requirements overcome (e.g. drop tests and pressure tests).
Mezonic had selected a multi-modal PE, based on data sheets and supplier information. But this was not successful. Mezonic then came to Norner for help due to our competences and detailed understanding of PE materials, processing conditions of injection moulding as well as root cause analysis by microscopy.
The first task was to investigate material morphology differences after moulding with a selection of the most promising PE grades which concluded with a recommendation of a material which worked well.
Norner helped Mezonic further in several optimisation stages of mould design and IM process parameters. Microscopy and analytical evaluations in this work could explain and identify preventive actions for;
After each stage, new prototypes were undergoing UN-testing followed by new investigations and improvements until the container passed the certification.
Containers are delivered in several colours and some pigment types and masterbatches have been more challenging than others. Mezonic experienced problems of dispersion and distribution of pigments, impurities and that different pigments influenced nucleation and thereby morphology and physical performance.
With the assistance from our microscopy team, all of these issues could be identified, understood and properly addressed. Each of them got solved.
The below pictures are some examples of microscopy investigations during this product development.
Figure 1: Sharp corner radiuses caused parts to crack. Example from study of an early mould design requiring improvements.
Figure 2: Laminar layer in the shear zone (cold orientation), which in worst cases may lead to delamination.
Figure 3: Delamination challenges at an early development stage. Better material selection and improving moulding conditions removed these problems.
Figure 4: Morphology differences caused by two different pigments.
Mezonic and Norner learned many lessons in this challenging development. Our best advice is to always include more detailed testing and microscopy investigations in the design- and process set-up phases. This reduces risks of failure, delays and saves significant costs long term.
For Mezonic it’s extremely important to have strong confidence in their products and this product is now well founded on deep insight and documentation.